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result(s) for
"Levy-Lahad, Ephrat"
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Hiding in Plain Sight — Somatic Mutation in Human Disease
by
King, Mary-Claire
,
Levy-Lahad, Ephrat
in
Adult
,
Autoimmune Diseases - genetics
,
Classification
2020
Beck et al. define an adult-onset inflammatory disorder that unites multiple clinical conditions with previously different diagnoses or with no diagnosis at all; their findings are now reported in the
Journal
.
1
The VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is defined by genotype, not by clinical phenotype. We agree with the authors that the names of disorders should be based on the responsible gene or pathway. Gene-based nosology best complements the discovery and deployment of genotype-targeted treatments for both inherited and noninherited forms of disease.
2
Beck et al. found that myeloid cells in each patient with the VEXAS syndrome . . .
Journal Article
A defect in GPI synthesis as a suggested mechanism for the role of ARV1 in intellectual disability and seizures
by
Segel Reeval
,
Renbaum, Paul
,
Beeri, Rachel
in
Convulsions & seizures
,
Defects
,
Encephalopathy
2020
Deficiency of the endoplasmic reticulum transmembrane protein ARV1 leads to epileptic encephalopathy in humans and in mice. ARV1 is highly conserved, but its function in human cells is unknown. Studies of yeast arv1 null mutants indicate that it is involved in a number of biochemical processes including the synthesis of sphingolipids and glycosylphosphatidylinositol (GPI), a glycolipid anchor that is attached to the C-termini of many membrane bound proteins. GPI anchors are post-translational modifications, enabling proteins to travel from the endoplasmic reticulum (ER) through the Golgi and to attach to plasma membranes. We identified a homozygous pathogenic mutation in ARV1, p.Gly189Arg, in two brothers with infantile encephalopathy, and characterized the biochemical defect caused by this mutation. In addition to reduced expression of ARV1 transcript and protein in patients’ fibroblasts, complementation tests in yeast showed that the ARV1 p.Gly189Arg mutation leads to deficient maturation of Gas1, a GPI-anchored protein, but does not affect sphingolipid synthesis. Our results suggest, that similar to mutations in other proteins in the GPI-anchoring pathway, including PIGM, PIGA, and PIGQ, ARV1 p.Gly189Arg causes a GPI anchoring defect and leads to early onset epileptic encephalopathy.
Journal Article
Essential Role of BRCA2 in Ovarian Development and Function
2018
The causes of ovarian dysgenesis remain incompletely understood. Two sisters with XX ovarian dysgenesis carried compound heterozygous truncating mutations in the BRCA2 gene that led to reduced BRCA2 protein levels and an impaired response to DNA damage, which resulted in chromosomal breakage and the failure of RAD51 to be recruited to double-stranded DNA breaks. The sisters also had microcephaly, and one sister was in long-term remission from leukemia, which had been diagnosed when she was 5 years old. Drosophila mutants that were null for an orthologue of BRCA2 were sterile, and gonadal dysgenesis was present in both sexes. These results revealed a new role for BRCA2 and highlight the importance to ovarian development of genes that are critical for recombination during meiosis. (Funded by the Israel Science Foundation and others.).
Journal Article
Mutant Adenosine Deaminase 2 in a Polyarteritis Nodosa Vasculopathy
by
Yalcinkaya, Fatos
,
Padeh, Shai
,
Klevit, Rachel E
in
Adenosine
,
Adenosine deaminase
,
Adenosine Deaminase - chemistry
2014
Adenosine deaminase 2 (ADA2) is a protein with at least two functions. It is a growth factor affecting leukocytes and endothelial cells and an enzyme that influences purine metabolism. This study shows that mutant ADA2 causes polyarteritis nodosa.
Polyarteritis nodosa, first described in 1866,
1
is a systemic necrotizing vasculitis that affects medium and small muscular arteries.
2
,
3
The ensuing tissue ischemia can affect any organ, including the skin, musculoskeletal system, kidneys, gastrointestinal tract, and the cardiovascular and nervous systems. Polyarteritis nodosa is usually diagnosed in middle age or later but can appear in childhood.
2
,
4
,
5
The diagnosis remains challenging despite classification criteria for adults
6
and children,
7
because polyarteritis nodosa frequently presents with nonspecific constitutional symptoms, and organ involvement and disease severity are highly varied. Polyarteritis nodosa is most often primary, but in adults it may be associated . . .
Journal Article
Preconception carrier screening yield: effect of variants of unknown significance in partners of carriers with clinically significant variants
by
Levy-Lahad, Ephrat
,
Carmi, Shai
,
Behar, Doron M.
in
Ashkenazi Jewish genetics
,
Biomedical and Life Sciences
,
Biomedicine
2020
Expanded preconception carrier screening (ECS) identifies at-risk couples (ARCs) for multiple diseases. ECS reports currently include only pathogenic/likely pathogenic variants (P/LPVs). Variants of unknown significance (VUS) are not reported, unlike genomic or chromosomal array test results in other post/prenatal settings. Couples who are P/LP and VUS carriers (P/LP*VUS) may be at risk, particularly in genes with high P/LP carrier rates. We examined the possible contribution of P/LP*cVUS (coding, nonsynonymous VUS) matings to ECS yield in an Ashkenazi Jewish cohort, a population with well-established preconception screening.
We analyzed 672 Ashkenazi Jewish genome sequences (225,456 virtual matings) for variants in three different gene sets and calculated the rates of P/LP*P/LP and P/LP*cVUS matings.
Across 180 genes, we identified 4671 variants: 144 (3.1%) P/LP and 1963 (42%) VUS. Across gene sets, the proportion of P/LP*P/LP and P/LP*cVUS ARCs was 2.7–3.8% and 6.8–7.5%, respectively.
Disregarding VUS in ECS may miss ARCs. Even if only 10% of couples currently classified as P/LP*cVUS are ultimately reclassified as P/LP*P/LP, ECS yield would increase by ≈20%. While current understanding of VUS precludes VUS reporting in ECS, these findings underscore the importance of VUS reclassification. This will crucially depend on enlarging population frequency databases, especially of affected individuals.
Journal Article
Population-based screening for breast and ovarian cancer risk due to BRCA1 and BRCA2
2014
In the Ashkenazi Jewish (AJ) population of Israel, 11% of breast cancer and 40% of ovarian cancer are due to three inherited founder mutations in the cancer predisposition genes BRCA1 and BRCA2 . For carriers of these mutations, risk-reducing salpingo-oophorectomy significantly reduces morbidity and mortality. Population screening for these mutations among AJ women may be justifiable if accurate estimates of cancer risk for mutation carriers can be obtained. We therefore undertook to determine risks of breast and ovarian cancer for BRCA1 and BRCA2 mutation carriers ascertained irrespective of personal or family history of cancer. Families harboring mutations in BRCA1 or BRCA2 were ascertained by identifying mutation carriers among healthy AJ males recruited from health screening centers and outpatient clinics. Female relatives of the carriers were then enrolled and genotyped. Among the female relatives with BRCA1 or BRCA2 mutations, cumulative risk of developing either breast or ovarian cancer by age 60 and 80, respectively, were 0.60 (± 0.07) and 0.83 (± 0.07) for BRCA1 carriers and 0.33 (± 0.09) and 0.76 (± 0.13) for BRCA2 carriers. Risks were higher in recent vs. earlier birth cohorts ( P = 0.006). High cancer risks in BRCA1 or BRCA2 mutation carriers identified through healthy males provide an evidence base for initiating a general screening program in the AJ population. General screening would identify many carriers who are not evaluated by genetic testing based on family history criteria. Such a program could serve as a model to investigate implementation and outcomes of population screening for genetic predisposition to cancer in other populations.
Significance Inherited mutations in the tumor suppressor genes BRCA1 and BRCA2 predispose to very high risks of breast and ovarian cancer. For carriers of these mutations, risk-reducing surgery significantly reduces morbidity and mortality. General population screening for BRCA1 and BRCA2 mutations in young adult women could be feasible if accurate estimates of cancer risk for mutation carriers could be obtained. We determined that risks of breast and ovarian cancer for BRCA1 and BRCA2 mutation carriers ascertained from the general population are as high as for mutation carriers ascertained through personal or family history of cancer. General screening of BRCA1 and BRCA2 would identify many carriers who are currently not evaluated and could serve as a model for population screening for genetic predisposition to cancer.
Journal Article
Snord 3A: A Molecular Marker and Modulator of Prion Disease Progression
by
Frid, Kati
,
Kahana, Esther
,
Lavon, Iris
in
Activating Transcription Factor 6
,
Animals
,
Biology
2013
Since preventive treatments for prion disease require early identification of subjects at risk, we searched for surrogate peripheral markers characterizing the asymptomatic phases of such conditions. To this effect, we subjected blood mRNA from E200K PrP CJD patients and corresponding family members to global arrays and found that the expression of Snord3A, a non-coding RNA transcript, was elevated several times in CJD patients as compared to controls, while asymptomatic carriers presented intermediate Snord3A levels. In the brains of TgMHu2ME199K mice, a mouse model mimicking for E200K CJD, Snord 3A levels were elevated in an age and disease severity dependent manner, as was the case for brains of these mice in which disease was exacerbated by copper administration. Snord3A expression was also elevated in scrapie infected mice, but not in PrP(0/0) mice, indicating that while the expression levels of this transcript may reflect diverse prion etiologies, they are not related to the loss of PrP(C)'s function. Elevation of Snord3A was consistent with the activation of ATF6, representing one of the arms of the unfolded protein response system. Indeed, SnoRNAs were associated with reduced resistance to oxidative stress, and with ER stress in general, factors playing a significant role in this and other neurodegenerative conditions. We hypothesize that in addition to its function as a disease marker, Snord3A may play an important role in the mechanism of prion disease manifestation and progression.
Journal Article
BRCA mutational status shapes the stromal microenvironment of pancreatic cancer linking clusterin expression in cancer associated fibroblasts with HSF1 signaling
2022
Tumors initiate by mutations in cancer cells, and progress through interactions of the cancer cells with non-malignant cells of the tumor microenvironment. Major players in the tumor microenvironment are cancer-associated fibroblasts (CAFs), which support tumor malignancy, and comprise up to 90% of the tumor mass in pancreatic cancer. CAFs are transcriptionally rewired by cancer cells. Whether this rewiring is differentially affected by different mutations in cancer cells is largely unknown. Here we address this question by dissecting the stromal landscape of
BRCA
-mutated and
BRCA
Wild-type pancreatic ductal adenocarcinoma. We comprehensively analyze pancreatic cancer samples from 42 patients, revealing different CAF subtype compositions in germline
BRCA
-mutated
vs. BRCA
Wild-type tumors. In particular, we detect an increase in a subset of immune-regulatory clusterin-positive CAFs in
BRCA
-mutated tumors. Using cancer organoids and mouse models we show that this process is mediated through activation of heat-shock factor 1, the transcriptional regulator of
clusterin
. Our findings unravel a dimension of stromal heterogeneity influenced by germline mutations in cancer cells, with direct implications for clinical research.
Cancer-associated fibroblasts are transcriptionally rewired by signals from the cancer cells, resulting in heterogeneous populations. Here the authors show that loss of BRCA function in pancreatic cancer cells leads to HSF1–dependent accumulation of immune-regulatory clusterin-positive cancer associated fibroblasts.
Journal Article
Vrk1 partial Knockdown in Mice Results in Reduced Brain Weight and Mild Motor Dysfunction, and Indicates Neuronal VRK1 Target Pathways
2018
Mutations in
Vaccinia-related kinase 1
(
VRK1
) have emerged as a cause of severe neuronal phenotypes in human, including brain developmental defects and degeneration of spinal motor neurons, leading to Spinal Muscular Atrophy (SMA) or early onset Amyotrophic Lateral Sclerosis (ALS). Vrk1 gene-trap partial Knockout (KO) mice (Vrk1
GT3/GT3
), which express decreased levels of
Vrk1
, are sterile due to impaired gamete production. Here, we examined whether this mouse model also presents neuronal phenotypes. We found a 20–50% reduction in
Vrk1
expression in neuronal tissues of the Vrk1
GT3/GT3
mice, leading to mild neuronal phenotypes including significant but small reduction in brain mass and motor (rotarod) impairment. Analysis of gene expression in the Vrk1
GT3/GT3
cortex predicts novel roles for VRK1 in neuronal pathways including neurotrophin signaling, axon guidance and pathways implicated in the pathogenesis of ALS. Together, our studies of the partial KO Vrk1 mice reveal that even moderately reduced levels of Vrk1 expression result in minor neurological impairment and indicate new neuronal pathways likely involving VRK1.
Journal Article
Minichromosome maintenance complex component 8 (MCM8) gene mutations result in primary gonadal failure
by
Dahary, Dvir
,
Abu-Rayyan, Amal
,
Tenenbaum-Rakover, Yardena
in
Adolescent
,
Alleles
,
Chromosomal Instability
2015
Background Primary gonadal failure is characterised by primary amenorrhoea or early menopause in females, and oligospermia or azoospermia in males. Variants of the minichromosome maintenance complex component 8 gene (MCM8) have recently been shown to be significantly associated with women's menopausal age in genome-wide association studies. Furthermore, MCM8-knockout mice are sterile. The objective of this study was to elucidate the genetic aetiology of gonadal failure in two consanguineous families presenting as primary amenorrhoea in the females and as small testes and azoospermia in a male. Methods and results Using whole exome sequencing, we identified two novel homozygous mutations in the MCM8 gene: a splice (c.1954-1G>A) and a frameshift (c.1469-1470insTA). In each consanguineous family the mutation segregated with the disease and both mutations were absent in 100 ethnically matched controls. The splice mutation led to lack of the wild-type transcript and three different aberrant transcripts predicted to result in either truncated or significantly shorter proteins. Quantitative analysis of the aberrantly spliced transcripts showed a significant decrease in total MCM8 message in affected homozygotes for the mutation, and an intermediate decrease in heterozygous family members. Chromosomal breakage following exposure to mitomcyin C was significantly increased in cells from homozygous individuals for c.1954-1G>A, as well as c.1469-1470insTA. Conclusions MCM8, a component of the pre-replication complex, is crucial for gonadal development and maintenance in humans—both males and females. These findings provide new insights into the genetic disorders of infertility and premature menopause in women.
Journal Article